High intensity modulated infrared radiation source

ABSTRACT

An internal combustion reciprocating engine having a highly transparent window replacing the head or a portion thereof provides a modulated infrared radiation source whereby the radiation from the combustion gases passing through the window is essentially fully modulated at varying frequencies.

' [541 HIGHINTENSITYMODULATED INFRARED 123/191'R,;191 M, 191 A, 11-9l-E, 1, 2; 8, 32

A, 195 0,198 E, 193 R, 193-11; 250/293;

1 7 References Cited ums!) STATES PATENTS 2,841,979 8/1958 Harbert.. 73/35 2,866,150 12/1958 Lewis"; 290/40 3,067,610 12/1962 Bockemuehl-et al;...' 73/35 X 7 m1] 3 3255 64 1451- July 23, 1974 OTHER PUBLICATIONS The lntemal Combustion Engine by Taylor & Taylor,

International Textbook Co 2nd Ed., 1961,,p. 182.

Materials Handbook,' 10th Edition, by Brady McGraw-Hill, 1 971,--pp. 34-37.

Society of Automotive Engines ,-Vehicle Emission, 1964, PP- 121,122.

The Internal Combustion Engine, Taylor v& Taylor,-.

PriinaryExamine r-G. R. Simmons Attorney, Agent, or Firm-Louis Etlinger; Richard 1. r

*Seligman ABSTRACT An internal combustion reciprocating engine having a' highly transparent window replacing the head or a portion thereof provides a modulated infrared radiation source whereby the radiation from the combustion gases passing through the window is essentially fully modulated at varying frequencies.

5 Claims, 4 Drawing Figures a I I '1 I I;

PATENTEB SHEET 10F 2 FIG! source itself.

vide a new and novel modulated source of infrared enan internal combustion reciprocating engine with a window having high transmissibility in .theinfrared a j I HIGH INTENSITY MODULATED INFRARED RADIATION SOURCE BACKGROUNDIVOF THE INVENTION Prior to the present invention the primary sources of 1 infrared radiation have been-the electrically powered or combustion heated blackbody and the arc lamp.- The primary drawback with such devices has been their inefficient use of relatively high levels of electrical input power for the electrical sources and the relatively complex materials'andassembly procedures required for the combustion heated sources.

To providecomplex modulation of the arc lamp output requires modulatorelectronics of undue complexity. Modulation of blackbody sources has generally been provided through the use of rotating choppers or vanes which. while satisfactory are relatively complex and costly, inefficient, or much larger than the basic SUMMARY OF THE'INvENTIoN' Accordingly, it is an object of this invention to pro- It is another object of this invention to provide a high temperature source of infrared radiation which is essentially fully modulated atvarying-frequencies.

It is a further object of this invention to provide a modulated infrared source having no additional modulators. I

Briefly,' a high intensity modulated infrared source is provided by replacing the head or portions thereof of spectrum.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description, taken in conjunction with the accompanying drawings, in which: FIG; 1 is asketch of the top view of a high intensity.

modulated infrared source in accordance with the present invention;

FIG. 2 is a sketch in section ofthesource of FIG. 1;

FIG. 3 is a sketch of the output waveform from a one cylinder engine; and

FIG. 4 is a schematic of themodulator of FIG. I having speed control.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, there is illustrated simplified diagrams of a basic highintensity modulated infrared source in accordance with the present invention. The source comprises an internalcombustion reciproeating engine of conventional form (only a portion of which is shown for clarity) having at least one cylinder 12 with an associated piston 14, intake and exhaust valves 16 and 18, and a spark plug 20. It

' should be noted that spark plug 20 is displaced from its conventional position at the centerlineof cylinder 12 so as not to block any radiation emitted from the device, as will be described hereinafter. Of course for diesel engines no spark plug is required.

' The head or a portion thereof of engine 10 is'removed anda window 22 is placed-over cylinder 12 held by, for example, brackets 24 and 26. Window 22 serves two functions; it contains the combustion gases andallows transmission of the radiation in the spectral region of interest. Preferably window 22 isconstructed of sapphire orpolycrystalline alumina. Quartz can be used;

however, it lacks the strength and the desired 3-5 micron transmissibility of .the other two materials.

A dish may bearranged about the window 22 to appropriately shape the pattern of radiation exiting there from. v t

The post-combustion gaseous mixture existing in an internal combustion engine approximates a 2,700 K radiator with a high emissivity in the 1-5 micron region, and essentially 1 in the region of rotational or vibration bands of any of the molecular species-present (CO N H O). The radiation is essentially modulated. at 100 percent levels, since the gases'are cooled sub stantially as the piston 14 retreats into the cylinder 12.

The temperature of the gases cools to essentially the temperature of the cylinder wallsof about 150? C at the completion of the intake stroke. Thus, modulation is achieved inherently withoutthe provision of additional .FIG. 3 is a sketch of the radiation pulse train exiting the window 22 and it is seen that essentially full modulation isachieved. The radiation pattern can be varied in pulse shape, frequency and duty cycle, To vary the pulse shape of the radiation the timing is altered by either advancing or retarding the spark from plug 20 in ofthe radiation is changed.

than required for optimum operation FIG. 4 illustrates schematically a preferred system wherein the output froma motor. 30 taken at a crank shaft 32 is mechanically coupled to a dc generator 34.

An ac generator could also be used. Accurate speed and, thus, frequency control is achieved by setting the dc voltage control 36 of the generator 34 and by varying the power thereof through a load resistor control 38. Preferably, the throttle to the engine is maintained wide open to supply as much combustion to the cylinders with the load being used as the limiting means. Generator 34 may be used to supply electrical power to an overall system by, for example, charging a bat- Fifi .1-.. M- a W When more than one cylinder is used, the duty cycle Optimum infrared radiation occurs theregionnear 2 "Although the invention has been described in conjunction with a four cycle internal combustion reciprodating engine, two cycle engines, diesel engines and rotating engines may be used. Thus, it is to be clearly understood that the description is made only by way of example, and not as a limitation of the scope of my invenv tion asset forth in the accompanying claims.

I claim:

1. A new use for an internal combustion engine having a window with good transmissibility in the infrared as a high intensity modulated infrared radiation source, comprising the steps of: i

i generating combustion gases within the internal combustion engine; and passing modulated infrared energy through the window of the engine while blocking substantially all of the visible energy from passing through the window. 2. The new use for an internal combustion engine as recited in claim 1,

further including the step of altering the modulated infrared energy passing through the window. 3. Thenew use for an internal combustion engine as reicted in claim 1, further including'the step of shaping the pattern of radiation passing through the window.

4. A high intensity modulated infrared radiation source, comprising; w

an internal combustion engine having at least a portion of the head removed thereby providing an at least one window enclosing said opening, said window having a high'transmissibility in the infrared such that essentially fully modulated infrared radiation is obtained from the combustion gases during operation. 

1. A new use for an internal combustion engine having a window with good transmissibility in the infrared as a high intensity modulated infrared radiation source, comprising the steps of: generating combustion gases within the internal combustion engine; and passing modulated infrared energy through the window of the engine while blocking substantially all of the visible energy from passing through the window.
 2. The new use for an internal combustion engine as recited in claim 1, further including the step of altering the Modulated infrared energy passing through the window.
 3. The new use for an internal combustion engine as reicted in claim 1, further including the step of shaping the pattern of radiation passing through the window.
 4. A high intensity modulated infrared radiation source, comprising; an internal combustion engine having at least a portion of the head removed thereby providing an opening to at least one cylinder thereof; a window enclosing the opening, said window having a high transmissibility in the infrared such that essentially fully modulated infrared radiation is obtained from the combustion gases during operation; and a reflector arrayed about said window for shaping the pattern of radiation exiting said window.
 5. A high intensity modulated infrared radiation source, comprising; an internal combustion engine having at least a portion of the head removed thereby providing at least one opening to at least two cylinders thereof; and at least one window enclosing said opening, said window having a high transmissibility in the infrared such that essentially fully modulated infrared radiation is obtained from the combustion gases during operation. 